[WebGL] Add a downlevel capability for rendering to floating point textures

wgpu-core/src/instance.rs

@@ -209,7 +209,11 @@ impl<A: HalApi> Adapter<A> {
     ) -> wgt::TextureFormatFeatures {
         use hal::TextureFormatCapabilities as Tfc;
 
-        let caps = unsafe { self.raw.adapter.texture_format_capabilities(format) };
+        let caps = unsafe {
+            self.raw
+                .adapter
+                .texture_format_capabilities(format, &self.raw.capabilities)
+        };
         let mut allowed_usages = format.describe().guaranteed_format_features.allowed_usages;
 
         allowed_usages.set(

wgpu-hal/src/dx11/adapter.rs

@@ -14,6 +14,7 @@ impl crate::Adapter<super::Api> for super::Adapter {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         todo!()
     }

wgpu-hal/src/dx12/adapter.rs

@@ -327,6 +327,7 @@ impl crate::Adapter<super::Api> for super::Adapter {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        _capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         use crate::TextureFormatCapabilities as Tfc;
 

wgpu-hal/src/empty.rs

@@ -84,6 +84,7 @@ impl crate::Adapter<Api> for Context {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         crate::TextureFormatCapabilities::empty()
     }

wgpu-hal/src/gles/adapter.rs

@@ -289,6 +289,10 @@ impl super::Adapter {
             wgt::DownlevelFlags::ANISOTROPIC_FILTERING,
             extensions.contains("EXT_texture_filter_anisotropic"),
         );
+        downlevel_flags.set(
+            wgt::DownlevelFlags::COLOR_ATTACHMENT_FLOAT,
+            extensions.contains("EXT_color_buffer_float"),
+        );
 
         let mut features = wgt::Features::empty()
             | wgt::Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES
@@ -603,6 +607,7 @@ impl crate::Adapter<super::Api> for super::Adapter {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         use crate::TextureFormatCapabilities as Tfc;
         use wgt::TextureFormat as Tf;
@@ -619,6 +624,17 @@ impl crate::Adapter<super::Api> for super::Adapter {
             unfilterable | Tfc::COLOR_ATTACHMENT | Tfc::MULTISAMPLE | Tfc::MULTISAMPLE_RESOLVE;
         let filterable_renderable = filterable | renderable | Tfc::COLOR_ATTACHMENT_BLEND;
         let storage = Tfc::STORAGE | Tfc::STORAGE_READ_WRITE;
+
+        let float_renderable = if capabilities
+            .downlevel
+            .flags
+            .contains(wgt::DownlevelFlags::COLOR_ATTACHMENT_FLOAT)
+        {
+            Tfc::COLOR_ATTACHMENT | Tfc::COLOR_ATTACHMENT_BLEND
+        } else {
+            Tfc::empty()
+        };
+
         match format {
             Tf::R8Unorm => filterable_renderable,
             Tf::R8Snorm => filterable,
@@ -628,37 +644,37 @@ impl crate::Adapter<super::Api> for super::Adapter {
             Tf::R16Sint => renderable,
             Tf::R16Unorm => empty,
             Tf::R16Snorm => empty,
-            Tf::R16Float => filterable,
+            Tf::R16Float => filterable | float_renderable,
             Tf::Rg8Unorm => filterable_renderable,
             Tf::Rg8Snorm => filterable,
             Tf::Rg8Uint => renderable,
             Tf::Rg8Sint => renderable,
             Tf::R32Uint => renderable | storage,
             Tf::R32Sint => renderable | storage,
-            Tf::R32Float => unfilterable | storage,
+            Tf::R32Float => unfilterable | storage | float_renderable,
             Tf::Rg16Uint => renderable,
             Tf::Rg16Sint => renderable,
             Tf::Rg16Unorm => empty,
             Tf::Rg16Snorm => empty,
-            Tf::Rg16Float => filterable,
+            Tf::Rg16Float => filterable | float_renderable,
             Tf::Rgba8Unorm | Tf::Rgba8UnormSrgb => filterable_renderable | storage,
             Tf::Bgra8Unorm | Tf::Bgra8UnormSrgb => filterable_renderable,
             Tf::Rgba8Snorm => filterable,
             Tf::Rgba8Uint => renderable | storage,
             Tf::Rgba8Sint => renderable | storage,
             Tf::Rgb10a2Unorm => filterable_renderable,
-            Tf::Rg11b10Float => filterable,
+            Tf::Rg11b10Float => filterable | float_renderable,
             Tf::Rg32Uint => renderable,
             Tf::Rg32Sint => renderable,
-            Tf::Rg32Float => unfilterable,
+            Tf::Rg32Float => unfilterable | float_renderable,
             Tf::Rgba16Uint => renderable | storage,
             Tf::Rgba16Sint => renderable | storage,
             Tf::Rgba16Unorm => empty,
             Tf::Rgba16Snorm => empty,
-            Tf::Rgba16Float => filterable | storage,
+            Tf::Rgba16Float => filterable | storage | float_renderable,
             Tf::Rgba32Uint => renderable | storage,
             Tf::Rgba32Sint => renderable | storage,
-            Tf::Rgba32Float => unfilterable | storage,
+            Tf::Rgba32Float => unfilterable | storage | float_renderable,
             Tf::Depth32Float
             | Tf::Depth32FloatStencil8
             | Tf::Depth24Plus

wgpu-hal/src/lib.rs

@@ -212,6 +212,7 @@ pub trait Adapter<A: Api>: Send + Sync {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        capabilities: &Capabilities,
     ) -> TextureFormatCapabilities;
 
     /// Returns the capabilities of working with a specified surface.

wgpu-hal/src/metal/adapter.rs

@@ -41,6 +41,7 @@ impl crate::Adapter<super::Api> for super::Adapter {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        _capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         use crate::TextureFormatCapabilities as Tfc;
         use wgt::TextureFormat as Tf;

wgpu-hal/src/vulkan/adapter.rs

@@ -1426,6 +1426,7 @@ impl crate::Adapter<super::Api> for super::Adapter {
     unsafe fn texture_format_capabilities(
         &self,
         format: wgt::TextureFormat,
+        _capabilities: &crate::Capabilities,
     ) -> crate::TextureFormatCapabilities {
         use crate::TextureFormatCapabilities as Tfc;
 

wgpu-types/src/lib.rs

@@ -1026,6 +1026,9 @@ bitflags::bitflags! {
         ///
         /// GLES/WebGL don't support this.
         const DEPTH_TEXTURE_AND_BUFFER_COPIES = 1 << 13;
+
+        /// Supports rendering to floating-point textures.
+        const COLOR_ATTACHMENT_FLOAT = 1 << 14;
     }
 }